Leno said that "whatever happened in the last 18 years disappeared" when the two comics got together to film their surprise Super Bowl ad last week.

"He was very gracious," Leno said Monday on his prime-time show, which ends Tuesday. "We talked about the old days. We told some jokes. It was really good to see him."

Letterman's bitterness at losing the "Tonight" show job to Leno nearly two decades ago has long been obvious to his CBS viewers. Leno is a frequent target of Letterman's jokes, which escalated during last month's drama over Leno reclaiming the "Tonight" show. Leno returned fire when the jokes got particularly rough.

It was a perfect setup for the Super Bowl promo. A grumpy Letterman complained to Oprah Winfrey about being at a lousy Super Bowl party, and the camera panned back to reveal Leno on the other side of a couch, saying, "he's just saying that because I'm here."

"No matter what animosity there is between comedians, a good joke is a good joke," Leno said.

Letterman, for his part, joked in his monologue about his mother wondering who it was sitting on the couch with Winfrey and Leno.

"People really thought this was big-time stuff, so I just want to take a second here now to thank the actors who played Oprah and also Jay Leno," he said on his show Monday. "They did a tremendous job."

Leno, a notorious workaholic, took a day off from his show to fly to New York to make the 15-second promo. He was driven to Letterman's studio on a black SUV and hustled in, wearing a disguise.

Leno said an NBC executive later approached him, saying the network believed Letterman was taping a secret show because someone entered the studio from a black SUV. NBC believed that Letterman was doing a show with President Barack Obama, he said.